Volcano animation – youtube embedded here
The animation shows eruption, and the processes leading up to the eruption, of a volcano. It explains that pressure of gases builds up underground until, eventually, it becomes so great that there is a violent explosion hurling dust and debris in to the sky and the surrounding area.
As the pressure is released the remaining gases in the magma (molten rock) cause lava to flow out and down the side of the volcano destroying everything in its path. Eventually the lava cools and forms a solid plug and the process begins again.
This being youtube an advert pops up after about 10 seconds. The ad only pops up once so if you let the animation play past the 10 second mark then pause it and drag the cursor back to the beginning it will not display the advert again.